In today's industrial environment, systems and equipment must perform at levels thought impossible a decade ago. Global competition forces the industry to continuously improve process operations, product quality, yield and productivity with fewer people than ever before. Production equipment must deliver unprecedented levels of reliability, availability, and maintainability as plant managers seek ways to reduce operational and support costs and to eliminate or minimize capital investments. In short, industry must invoke new measures to improve production, performance, safety and reliability while minimizing costs and extending the operational life of new and aging equipment.
Valves and pneumatic actuators are important elements in every process industry. WO2008/078323 by same Applicant discloses a device and system for wirelessly monitoring the status, particularly the angular position of valves in an industrial facility. More particularly, this publication discloses an add-on monitoring device which is mounted on a ball valve (also known in the art as a “quarter turn valve”), and a network which is formed from plurality of such monitoring devices. The monitoring devices operate in a short range wireless network, such as Bluetooth, Zigbee, ISA100 or Wireless HART, etc. Each monitoring device reports to a control center via the short range network the status of each respective ball valve.
The monitoring devices of WO2008/078323 may be attached to manually operated quarter turn valves, or to quarter turn valves that are remotely actuated by means of valve actuation devices. The fact that the transmitter of the monitoring device of WO2008/078323 transmits the status of the quarter turn valve either periodically, or upon event, enables the transmitter of the device to stay in a “sleeping state” most of the time, and to “wake up” only at times of necessity for transmitting the status of the valve. In this manner of operation, a relatively compact battery can be used, and such battery can last up to several years.
In another typical aspect, the valve may be rotated (either manually or by means of an actuator) to any desired angular position within the range of 0° to the 90°. The monitoring device of WO2008/078323 is capable of wirelessly reporting in a very high degree of accuracy, the angular position of the stem. In the case of automatic operation, the monitoring device provides a feedback to the control center which enables it to confirm that the desired angular positioning of the valve has indeed been appropriately set.
In another aspect, PCT/IL2013/050494 discloses a system for predicting a future failure of a quarter turn valve actuator. In general, the system of PCT/IL2013/050494 comprises: (a) a sensor for, upon receipt a control command at the actuator, continuously sensing the angular position of the stem of the valve, and conveying to a monitoring unit a respective angular variation signal; and (b) a monitoring unit which comprises: (b1) a sampling unit for receiving said angular variation signal, and producing a transition vector which comprises periodical samples from said angular variation signal; (b2) a local storage for storing nominal transitional values for said actuator-valve pair; and (b3) a local comparator unit for comparing at least a portion of said transitional vector with a corresponding stored set of nominal transitional values, and if a difference above one or more predefined threshold values is determined, issuing an alert for a potential failure of said actuator.
As noted, both WO2008/078323 and PCT/IL2013/050494 are targeted for operation with quarter turn valves. More specifically, WO2008/078323 provides a monitoring device which determines and reports the angular position of a quarter turn valve, and PCT/IL2013/050494 predicts a possible failure of an actuator for a quarter turn valve.
In similarity to quarter turn valves, linear valves are also widely used in the industry for controlling the flow of fluids. However, the monitoring and prediction devices of WO2008/078323 and PCT/IL2013/050494 respectively are incapable of performing said monitoring or prediction tasks in the linear valves environment, as they are both designed for operation only when an angular variation of a stem occurs, as is the case in the quarter turn valves environment.
Typically, a stem of a linear valve is linearly displaced by a distance of several tens of millimeters (for example, 25 millimeters) when switching from an open state to a closed state, or vice versa. In order to monitor the state of the valve, an extension from the stem is typically provided to activate a pair of micro-switches. A first switch from said pair of micro-switches is provided at a first end of the supposed displacement of the extension, while the second switch from said micro-switches is provided at the opposite end of the supposed displacement. In such a manner, the states of the two micro switches respectively provide indication as to whether the valve is in its close state or in its open state.
Linear valves are widely used in the food industry, for example, in the dairy industry. When used in the dairy industry, a continuous and extreme care is required to be maintained in order to keep the pipes, valves, and all associated internal components perfectly clean during operation, in order to avoid development of bacteria. This is particularly important in view of a mass production and fast distribution and use that are typical to products the dairy industry. For example, if cleaning of the pipes and valve components is not perfectly maintained, the health of tens of thousands of people may simultaneously be affected within a very short period (in the order of several hours), even before the failure and contamination is detected. To maintain the pipes, valves, and internal components hygienic in the dairy industry, typically a “double valve” structure is used, and a procedure known as “double lifting” is performed once every several hours. A “double lifting valve” is a structure of two linear valves that are positioned in a channel between two pipes. In the main mode of operation, said two valves may be displaced simultaneously to open the channel between the two pipes thus allowing the material to flow from one pipe to the other. When the two valves are not displaced, there is no flow of material between the pipes due to the seals on the valves. In another mode of operation, when the two valves are in close position, each of said two valves may be displaced independent from the other, while the other valve remains stationary and closed. During times of normal dairy production, an actuator may close or open a channel between two pipes by displacing simultaneously the two valves to a same direction thereby to enable the flow of material between the pipes. The Cleaning In Process (CIP) procedure (which is typically performed once every several hours) is a two-step procedure. The CIP procedure always begins from a state where the two valves are in close position. During the first step, the actuator partially displaces a first of said two valves to a first direction to within the first pipe, while the second valve remains stationary in a state of channel closure. Following the partial displacement, said first valve is flushed by a flow of detergent and water within the first pipe. Upon completion of the flushing of the first valve, the actuator again performs a partial displacement by returning this valve to a position of channel closure (at this stage the channel closure is maintained by both of said two valves). The second step of the CIP procedure is initiated by the actuator partially displacing the second of said two valves to a second direction to within the space of said second pipe, while the first valve remains stationary in a state of channel closure. Following the partial displacement, said second valve is now flushed by a flow of detergent and water within the second pipe. Upon completion of flushing of the second valve, the actuator again performs a partial displacement by returning this valve to a position of channel closure, and the flushing procedure is completed (at this stage again the channel closure is maintained by both of said two valves).
The main open-close linear displacements are typically in the order of 25-50 mm. In contrast, the partial (CIP) displacements are typically much smaller, in the order of 5-10% of said main open-close displacement. More specifically, while the main open-close displacements are in the order of at least 25-50 mm (depending on the specific application), said partial displacements are in the order of 2-4 mm. Unfortunately, said micro-switches arrangement discussed above is capable of sensing displacements in the order of at least 15-20 millimeters, while being incapable of sensing such short displacements of 2-4 millimeters. As a result of this limitation, said two-step CIP procedure is performed without feedback to the control center, i.e., without monitoring the partial displacements of the valve, and without ensuring that the displacements have indeed took place. Clearly, such manner of operation without feedback poses significant risks to the manufacturer (of losing products and material) and to the health of the public. Moreover, the procedure as presently used does not enable any prediction with respect to components failures.
It is therefore an object of the present invention to provide a wireless monitoring system which is particularly adapted for linear valves.
It is still another object of the present invention to provide a wireless monitoring system which is capable of monitoring short displacements of linear valves, as performed particularly during the cleaning procedures in the food industry.
It is still another object of the present invention to provide a monitoring system which is capable of detecting failures in the operation of linear valves.
It is still another object of the present invention to provide a monitoring system which is capable of predicting failures in the operation of linear valves.
It is still another object of the present invention to provide said monitoring, failure detection, and prediction system, which can be easily adapted for linear valves presently in the market.
It is still another object of the present invention to provide said monitoring, failure detection, and prediction system, which is an add-on system.
Other objects and advantages of the invention will become apparent as the description proceeds.